Many techniques have been proposed for providing x-y actuation, that is, scanning: see, for example, WO 00/75712. Actuation in the z or depth direction is also often required, particularly in endoscopy and microscopy and, in particular, in confocal systems. In one existing approach, z depth adjustment is provided by manual adjustment of the position of an objective lens. In bench-top systems this may be done by direct adjustment; in hand held devices this is done, in one existing system, by means of a mechanical cam system operated by the user. In confocal microscopy systems, a z depth adjustment mechanism is required to enable the operator to focus the confocal point within a specimen at different focal plane depths.
However, existing z-actuator systems are inappropriate for miniaturized confocal endoscopes and other compact systems where dimensions (and, in particular, diameter) are required to be minimized, or where, as in endoscopy, the length of the rigid head should be as short as possible.
It is an object of the present invention to provide a z actuator that is controllable in the z axis but provides some flexibility in lateral directions.